1. Field of the Invention
The present invention relates to an electronic device having a projector module. Particularly, the present invention relates to an electronics device having a projector module capable of performing desktop projection.
2. Discussion of the Background
Use of projectors as tools for home theaters and meetings using personal computers is rapidly spreading. Recently, small portable projectors to be used in combination with notebook computers have been developed. Such portable projectors are preferably used for meetings (such as presentations) held at a room having no projector.
Under such circumstances, there are movements such that a projector is incorporated in electronics device such as mobile phones. By incorporating a projector into such mobile electronics devices, the convenience of the devices can be dramatically enhanced.
Such mobile electronics devices having a projector are considered to be used as follows. If a person has a mobile phone having a projector module, the person will project an image on a plane (such as wall or desktop) while holding the phone with a hand. In this case, there are problems to be solved such that the image is blurred due to hand movement, and the hand is damaged by heat generated by the phone. Therefore, such a mobile phone will be typically used by being set on an installation surface such as desktops. If such a mobile phone is set on a desk, it will be typical that an image is projected on a vertical screen. In this case, if the projector module is small and has a low output power, the vertical screen has to be set near the mobile phone.
Alternatively, it is possible to project an image on the desk on which the mobile phone is set. FIG. 17 illustrates a mobile phone projecting an image on a desk on which the mobile phone is set. Since this projection method uses no screen, the method can be preferably used for small-size conference rooms. In addition, since an image is projected on a place near the projector module, the output power of the projector module can be decreased.
In such a projection system, the operating portion (such as operation buttons) of the electronics device (mobile phone) in which the projector module is set will be used as an interface for manipulating output images. However, the method has the following drawbacks. Specifically, it is difficult to operate the operating portion of such an electronics device without moving the device itself. If the device is moved by an operation, the image is also moved during the operation and therefore it is difficult to watch a projected image. In addition, since such an electronics device is small in size, heat generated by the projector module will be transmitted to the operating portion. Therefore, it is necessary to solve the problems.
Thus, it is inconvenient to perform an image projection operation using the electronics device itself. It is considered to use a remote controller for such an image projection operation, but an electronics device in combination with a remote controller is inferior in mobility and cost.
Therefore, it will be most preferable to perform an operation by directly touching a portion of the projected image (the method is hereinafter referred to as a projected image touching method). In this case, the electronics device needs to have a module detecting that the predetermined portion of the projected image is touched with a finger or the like. By using such a module, whether the predetermined portion of an image projected on a plane is touched can be determined.
Published unexamined Japanese patent applications Nos. (hereinafter referred to as JP-As) 2007-219966, 2007-133835 and 2005-165804 have disclosed input devices using such a projected-image touching method. These devices relate to inputting using a virtual keyboard, which has been commercialized and in which a keyboard image is projected on a desk. When a key of the keyboard image is touched, the touched key can be identified by a reading sensor provided in the electronics devices. These devices can project only a keyboard pattern can be projected. Specific examples of the projector of the electronics devices include projectors in which a laser beam irradiates a special diffraction grating to form a keyboard pattern image. The keyboard pattern image changes depending on the pattern of the diffraction grating. From this point of view, the projectors are different from data projectors.
Read sensors for determining what key is pushed in such a virtual keyboard typically have the configuration as illustrated in FIG. 18. Referring to FIG. 18, an infrared laser 62 emits an infrared laser beam while performing scanning on a plane (i.e., infrared ray plane) located slightly above a surface 61 of a desk on which a keyboard image is projected by a projector module 60. If an operator sets a finger so as to touch a key of the projected keyboard image, the infrared laser beam is reflected by the set finger. The thus reflected infrared laser beam is detected with an infrared ray sensor 63 (such as CCD cameras) provided at a position above the infrared ray plane. The key touched by the finger can be determined depending on the position of the light receiving portion of the CCD cameras receiving the reflected infrared laser beam.
The devices disclosed in JP-As 2007-219966, 2007-133835 and 2005-165804 need to have an infrared laser source, an element for converting the laser beam so as to have a planar profile, and a two-dimensional CCD camera for detecting the reflected laser beam. Therefore, the devices need to have two optical windows, one of which is used for emitting an infrared laser beam and the other of which is used for the CCD camera receiving the reflected infrared laser beam. Therefore, appearance of the electronics devices (such as mobile phones) is not good.
JP-A 2007-053420 discloses an image processing device having the same reading function as the above-mentioned key reading function. However, the image projected by the device is not limited to a keyboard image. The image projection section of the device projects a two-dimensional image using a laser beam scanned by two polygon mirrors. The read sensor thereof is an independent module similarly to the devices using a virtual keyboard. Therefore, the device needs to have an infrared laser source, an element for converting the laser beam so as to have a planar profile, and a two-dimensional CCD camera for detecting the reflected laser beam. It is described therein that the laser beam converting element is a scanning member for scanning a laser beam, and polygon mirrors are exemplified as the scanning member.
The image processing device has to have three polygon mirrors, two of which are used for the image projecting section and one of which is used for the read sensor. Therefore, the image processing device has high costs.
Further, published Japanese translation (Kohyo No. 2007-528023) of a PCT application discloses a laser projection display, which scans a laser beam using a biaxial MEMS (Micro Electro Mechanical Systems) mirror and in which reading of a key of a virtual keyboard image is performed using an image capture. The laser projection display seems to have a low accuracy in detecting the height of a finger, namely the accuracy in determining whether a key of a virtual keyboard is pushed is low. Therefore, detection errors may often occur.
Image projection techniques similar to the technique disclosed in Kohyo No. 2007-528023, such that when a person steps on an image projected on a floor by a projector provided on a ceiling, the image is changed to another image have been used for amusement places, etc. Although the techniques have different principles, the typical principle is that when detecting a foot by its height using a three-dimensional image capture, the projected image is changed. Another principle is that an image of an object is caught by a CCD sensor, and the pixels of the CCD sensor are analyzed to determine the distance between the sensor and the object for every pixels using a TOF (Time of Flight) method, thereby obtaining three dimensional data of the object. The accuracy in measuring a distance by this method is insufficient for determining the height of a foot (determining the height of a foot is a severe distance measuring operation). Thus, the technique has low detection accuracy.
A variety of patent applications have disclosed projectors equipped with a distance measuring sensor. Almost all the projectors use a technique such that the distance between the screen and the projector is detected, and then a key stone correction is made.
Because of these reasons, a need exists for an electronics device in which an inputting operation is performed by a projected image touching method with a high degree of reliability and which has good appearance and low costs.